Fibre Optics

About 7 years ago we had a fibre optic connection installed in our home. The router, provided by our ISP, is a Fritz!Box 5490, for which I pay about 4€ a month. To my surprise I realised a few weeks ago that the last time it received security updates was in 2023! Time for a new router.

This time I decided to buy the router, rather than rent it. Since my current router has a direct fibre connection I had choices to make. In fact many more than I had anticipated.

Router: DSL with ONT box vs Direct Fibre

Since my internet connection is fibre direct to the home, currently I need a router which can be connected directly to a fibre optic connection. This severely limits the number of routers available, since all routers come with a DSL connection, but few come with a fibre socket.

My ISP said they can provide for free an Optical Network Terminal (ONT) which converts the fibre signal to a DSL signal. They would provide a TP-Link MC220L ONT unit together with an SFP-GE-BX laser module. It took me a while to understand all this. The former is a box that connects the two signals together. The latter is a "stick" that you push inside this box and does the actual signal conversion. It's separate because there are different types of optical signals (see AON vs GPON below) and you need a different stick depending on that signal.

The ONT box needs it's own power supply, which is not a problem in the location I would need to install it. Nevertheless in the end I decided to go for a fibre router to avoid the need another box in that location.

AON vs GPON

Not so much a choice, as needing to know the fibre optic network I am connected to: AON or PON. Turns my connection is AON.

SC vs LC

Having decided to go with another direct fibre optic connecion to the router, I bought the Fritz!Box 5490 Pro.

When I tried to connect the cable from the old router to the new one, it didn't fit! The old connector was blue, the new one green. Apparently the colours mean something:

  • Blue = SC connector type = Subscriber connector
  • Green = LC connector type = Lucent connector

Who knew?

Whilst there was a green connector in the box, it of course also didn't fit the wall mounted end point for the fibre into my house. So I needed a new cable with one end blue and the other green, or an adaptor.

Time for an Amazon search.

APC vs UPC

Turns out there are plenty of connectors and it is not obvious that there is another level of detail to pay attention to. Reading the description of the connectors I soon realised there was mention of APC and UPC. See this wiki article and this more detailed explanation.

What's this?

Beyond the connector type (ie the shape of the hole into which the cable gets inserted), there are also different "endfaces":

  • PC = Physical Contact
  • UPC = Ultra Physical Contact
  • APC = Angled Physical Contact

Combining this with the SC or LC connector and you end up with several connector variants:

  • SC/APC
  • SC/UPC
  • LC/APC
  • LC/UPC

There are adapter possibilities to mix and match between these!

The 5790 Pro needs an LC/APC connector. And my old 5490 used an SC/PC connetor.

PC is an old endface type and has been replaced by UPC. Apparently you can connect a PC to UPC connector type. So I bought a SC/UPC to LC/APC converter on Amazon.

Connecting it all up at home unfortunately didn't work. The router was not able to connect to the ISPs network. A ticket with the ISP has been raised. To be continued...

Tagged: